choosing a new residential steam boiler - help!

I have a 100-year old (?) original steam boiler that may be leaking (the holding tank) and if so, will need to be replaced. There are a few companies that make residential steam boilers, but how do the boilers differ and how do I compare them? For efficiency, ease of use, reliability, durability, warranties, maintenance, etc.?

I have 2 very different estimates from 2 different installers. One only installs the Weil McLain boilers, the other only installs Burnham boilers.

The specific boilers recommended are:

Weil McLain EG-50 175,000 BTU for $7485.00(with a Tjernlund side vent kit for the boiler and water heater for $2,250.00 and a new McDonnell Miller 47-2 auto water level control for $950.00)

Burnham Pin ING 175,000 BTU Steam Boiler(with Tjernlund venting and power vent controls and re-venting the existing water heater, combustion air as per code, connect to existing gas and water piping, electrical wiring with new thermostat) for a total of $15,052.00.

What is the difference between these two (other than the obvious price difference), and are there other boilers I should consider?